推力::顺序 - 如何增加每个N元素后的步骤 [英] thrust::sequence - how to increase the step after each N elements

问题描述

我使用

thrust::sequence(myvector.begin(), myvector.end(), 0, 1)

并实现好的有序列表，如：

and achieve good ordered list like:

0, 1, 2, 3, 4

问题是如何实现这样的列表（最好的方式？）

My question is how can I achieve such a list below (the best way?)

0, 0, 0, 1, 1, 1, 2, 2 ,2, 3, 3, 3

我知道如何使用函子，所以请不要尝试用函子回答它。我想知道如果在Thrust中有一个优化的方法，或者我错过了一个简单的方法。

I know how to make it with functors, so please do not try to answer it with functor. I want to learn if there is an optimized way for it in Thrust, or am I missing a simple way..

推荐答案

像这样：

thrust::device_vector<int> myvector(N);

thrust::transform( thrust::make_counting_iterator(0),
                   thrust::make_counting_iterator(N),
                   thrust::make_constant_iterator(3),
                   myvector.begin(),
                   thrust::divides<int>() );

（免责声明，用浏览器编写，未经编译或测试，自行承担风险）

(disclaimer, written in browser, never compiled or tested, use at own risk)

应该通过计算 [0..N] // 3 给出您要查找的序列， code> myvector 。

should give you the sequence you are looking for by computing [0..N]//3 and outputting the result on myvector.

看到您在编译您的版本时遇到问题，这里是一个编译和运行的完整示例：

Seeing as you are having trouble compiling your version, here is a complete example which compiles and runs:

#include <thrust/device_vector.h>
#include <thrust/transform.h>
#include <thrust/functional.h>
#include <thrust/iterator/counting_iterator.h>
#include <thrust/iterator/constant_iterator.h>
#include <cstdio>

int main(void)
{
    const int N = 18, M = 3;
    thrust::device_vector<int> myvector(N);

    thrust::transform(  thrust::make_counting_iterator(0),
                        thrust::make_counting_iterator(N),
                        thrust::make_constant_iterator(M),
                        myvector.begin(),
                        thrust::divides<int>() );

    for(int i=0; i<N; i++) {
        int val = myvector[i];
        printf("%d %d\n", i, val);
    }
    return 0;
}

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